1. Field of the Invention
The present invention relates to a semiconductor memory device, for example, a semiconductor memory device for storing data as a state of majority carriers accumulated in a channel body of a transistor formed in a substrate such as an SOI substrate, and method of manufacturing the same.
2. Description of the Related Art
A semiconductor memory device that can achieve dynamic storage in a simpler cell structure has been proposed recently for the purpose of replacing DRAM (JP 2002/343886A, FIGS. 1-4). A memory cell includes a transistor having a floating body (channel body) formed in an SOI substrate. The memory cell can achieve binary storage as a first data state (for example, data “1”) in which excess majority carriers are accumulated in the body and a second data state (for example, data “0”) in which excess majority carriers are released from the body.
Such the memory cell is called a “FBC (floating body cell)” and the semiconductor memory device using the FBC is called a “FBC memory”. The FBC memory is not provided with a capacitor that is employed in a normal DRAM. Therefore, it has a simple cell array structure and a small unit cell area, and accordingly it can be highly integrated easily.
Similar to other conventional semiconductor memory devices such as DRAM, the FBC is also desired for quick writing of data and preventing occurrences of data destruction.